Robotic cleaning device with retractable side brush

ABSTRACT

A robotic cleaning device having a main body, a propulsion system configured to move the robotic cleaning device over a surface to be cleaned, a controller configured to control the propulsion system to move the robotic cleaning device over the surface to be cleaned, at least one rotatable side brush arranged to sweep debris from the surface to be cleaned, and a mechanism configured to at least partly retract the at least one rotatable side brush into a space arranged inside the main body upon receiving a control signal from the controller, such that the rotatable side brush is moved out of contact with the surface to be cleaned.

TECHNICAL FIELD

The invention relates to a robotic cleaning device being equipped with at least one retractable side brush.

BACKGROUND

Robotic vacuum cleaners are known in the art, which are equipped with drive means in the form of motors for moving the cleaner across a surface to be cleaned. The robotic vacuum cleaners are further equipped with intelligence in the form of microprocessor(s) and navigation means for enabling an autonomous behaviour such that the robotic vacuum cleaners freely can move around and clean a space in the form of e.g. a room.

Traditionally, robotic vacuum cleaners have been arranged with circular-shaped main bodies. Such a robot having co-axial drive wheels at the centre of its body has the advantage that it is easy to control and cannot easily get stuck since it always can rotate 180° and go back the same way it came.

However, the circular-shaped main body makes them unsuitable for cleaning corners or edges where a floor meets a wall since these circular vacuum cleaners due to their shape cannot move into a corner or close enough to a wall, or other objects around which cleaning is required such as e.g. chair legs.

An example of a robotic vacuum cleaner aiming at solving this problem is disclosed in US 2013/0086760, the main body of which is circular-shaped, and which robotic vacuum cleaner is equipped with rotatable side brushes which are arranged at a bottom side of the main body in a front section of the robotic vacuum cleaner for sweeping debris out of corners where the robotic vacuum cleaner cannot reach. Further, each rotatable side brush is mounted on a respective pivotable arm which can be pivoted to have the side brushes extend in front of the main body to reach even further. Side brushes have also been used for robotic vacuum cleaner having other shapes, such as triangular shapes.

Now, a problem with side brushes is that they have a tendency of performing poorly on certain types of surfaces, such as for instance carpets where carpet fibres can get entangled with the rotating brushes. Further, carpets also wear the side brushes down thereby impacting their durability and may even cause unintentional lift of the robot, not letting it sink into the carpet to clean it thoroughly. Another disadvantage is that the side brushes hamper the capability of the robot to climb over objects such as thresholds, cables and carpet edges.

SUMMARY

An object of the invention is to solve, or at least mitigate this problem in the art, and thus to provide a robotic vacuum cleaner which is not hampered by its side brushes.

This object is attained in a first aspect of the invention by a robotic cleaning device comprising, a main body, a propulsion system configured to move the robotic cleaning device over a surface to be cleaned, a controller configured to control the propulsion system to move the robotic cleaning device over the surface to be cleaned, at least one rotatable side brush arranged to sweep debris from the surface to be cleaned. The robotic cleaning device further comprises a mechanism configured to at least partly retract said at least one rotatable side brush into a space arranged inside the main body upon receiving a control signal from the controller, such that the rotatable side brush is moved out of contact with the surface to be cleaned.

Advantageously, by being capable of retracting the side brush(es), the robotic cleaning device can avoid a situation where the side brush entangles with fibres of a carpet, or to improve the capability of the robot to climb over objects such as thresholds, cables and carpet edges, or simply enable to not permanently have the side brush contacting the surface over which the robotic cleaning device moves.

In an embodiment, the mechanism further comprises a retractable member coupled to the at least one rotatable side brush arranged to retract the at least one rotatable side brush into said space, and an actuator (e.g. a motor) arranged to move the retractable member into, or out of, said space upon receiving a control signal from the controller.

In an embodiment, said at least one rotatable side brush is arranged to be retractable into the space inside the main body in an axial direction with respect to the rotational axis of the side brush.

In an embodiment, said space is cylindrically shaped and the mechanism configured to retract said at least one rotatable side brush comprises a threaded rod located in the cylindrically shaped space, an annular threaded member to which the at least one rotatable side brush is attached, the annular threaded member being arranged to engage with the threaded rod, and an actuator (e.g. a motor) configured to rotate the threaded rod. Further, a diameter of the cylindrically shaped space is adapted to a dimension of the at least one rotatable side brush such that friction is created between the side brush and an interior of the cylindrically shaped space, thereby at least partly preventing the at least one rotatable side brush (114) to rotate when in contact with said interior, wherein said friction causes the annular threaded member to move along the threaded rod to extend out from the space in order to have the at least one rotatable side brush rotate and sweep the debris from the surface to be cleaned upon the threaded rod rotating in a first direction, the threaded annular member moving along the threaded rod until it reaches an end member of the threaded rod preventing the annular threaded member to move out of threaded engagement with the threaded rod, and friction between the at least one rotating side brush and the surface to be cleaned causes the annular threaded member to move along the threaded rod to retract into the space upon the threaded rod rotating in a second direction. Advantageously, the same actuator is used for retracting the side brush and for rotating the side brush.

In a further embodiment, the mechanism further comprises a spring arranged between the annular threaded member and the end member.

In still an embodiment, the robotic cleaning device further comprises an opening in a bottom side of the main body via which debris is removed from the surface, wherein the at least one rotatable side brush is arranged adjacent to the opening.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a/an/the element, apparatus, component, means, step, etc.” are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is now described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 shows a robotic cleaning device according to an exemplifying embodiment of the present invention;

FIG. 2 shows the robotic cleaning device of FIG. 1 in a front view;

FIG. 3 shows retraction of a rotatable side brush in an embodiment;

FIG. 4 shows retraction of a rotatable side brush in another embodiment;

FIGS. 5a and b shows retraction/extension of a rotatable side brush in an embodiment;

FIGS. 6a and b shows extension of a rotatable side brush in an embodiment; and

FIG. 7 shows a spring-biased side brush in an embodiment.

DETAILED DESCRIPTION

The invention will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein;

rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout the description.

The invention relates to robotic cleaning devices, or in other words, to automatic, self-propelled machines for cleaning a surface, e.g. a robotic vacuum cleaner, a robotic sweeper or a robotic floor washer. The robotic cleaning device according to the invention can be mains-operated and have a cord, be battery-operated or use any other kind of suitable energy source, for example solar energy.

Even though it is envisaged that the invention may be performed by a variety of appropriate robotic cleaning devices being equipped with sufficient processing intelligence, FIG. 1 shows a robotic cleaning device 100 according to an embodiment of the present invention in a bottom view, i.e. the bottom side of the robotic cleaning device is shown. The arrow indicates the forward direction of the robotic cleaning device 100 being illustrated in the form of a robotic vacuum cleaner.

The robotic cleaning device 100 comprises a main body in housing components such as a propulsion system comprising driving means in the form of two electric wheel motors 115 a, 115 b for enabling movement of the driving wheels 112, 113 such that the cleaning device can be moved over a surface to be cleaned. Each wheel motor 115 a, 115 b is capable of controlling the respective driving wheel 112, 113 to rotate independently of each other in order to move the robotic cleaning device 100 across the surface to be cleaned. A number of different driving wheel arrangements, as well as various wheel motor arrangements, can be envisaged. It should be noted that the robotic cleaning device may have any appropriate shape, such as a device having a more traditional circular-shaped main body, or a triangular-shaped main body. As an alternative, a track propulsion system may be used or even a hovercraft propulsion system. The propulsion system may further be arranged to cause the robotic cleaning device 100 to perform any one or more of a yaw, pitch, translation or roll movement.

A controller 116 such as a microprocessor controls the wheel motors 115 a, 115 b to rotate the driving wheels 112, 113 as required in view of information received from an obstacle detecting device (not shown in FIG. 1) for detecting obstacles in the form of walls, floor lamps, table legs, around which the robotic cleaning device must navigate. The obstacle detecting device may be embodied in the form of a 3D sensor system registering its surroundings, implemented by means of e.g. a 3D camera, a camera in combination with lasers, a laser scanner, etc. for detecting obstacles and communicating information about any detected obstacle to the microprocessor 116. The microprocessor 116 communicates with the wheel motors 115 a, 115 b to control movement of the wheels 112, 113 in accordance with information provided by the obstacle detecting device such that the robotic cleaning device 100 can move as desired across the surface to be cleaned.

Further, the robotic cleaning device 100 is equipped with one or more batteries 117 for powering the different components included in the cleaning device 100. The one or more batteries 117 are charged via a charging station into which the robotic cleaning device 100 docks.

Moreover, the main body in of the robotic cleaner 100 comprises a suction fan 120 creating an air flow for transporting debris to a dust bag or cyclone arrangement (not shown) housed in the main body via the opening 118 in the bottom side of the main body in. The suction fan 120 is driven by a fan motor 121 communicatively connected to the controller 116 from which the fan motor 121 receives instructions for controlling the suction fan 120. The main body 111 is further arranged with one or more rotatable side brushes 114 adjacent to the opening 118. The rotation of the side brush 114 is typically accomplished by a separate motor (not shown in FIG. 1), or a brush roll motor.

With further reference to FIG. 1, the controller/processing unit 116 embodied in the form of one or more microprocessors is arranged to execute a computer program 125 downloaded to a suitable storage medium 126 associated with the microprocessor, such as a Random Access Memory (RAM), a Flash memory or a hard disk drive. The controller 116 is arranged to carry out a method according to embodiments of the present invention when the appropriate computer program 125 comprising computer-executable instructions is downloaded to the storage medium 126 and executed by the controller 116. The storage medium 126 may also be a computer program product comprising the computer program 125. Alternatively, the computer program 125 may be transferred to the storage medium 126 by means of a suitable computer program product, such as a digital versatile disc (DVD), compact disc (CD) or a memory stick. As a further alternative, the computer program 125 may be downloaded to the storage medium 126 over a wired or wireless network. The controller 116 may alternatively be embodied in the form of a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a complex programmable logic device (CPLD), etc.

FIG. 2 shows a front view of the robotic cleaning device 100 of FIG. 1 in an embodiment of the present invention illustrating the previously mentioned obstacle detecting device in the form of a 3D sensor system comprising at least a camera 123 and a first and a second line laser 127, 128, which may be horizontally or vertically oriented line lasers. Further shown is the controller 116, the main body 111, the driving wheels 112, 113, and the rotatable side brush 114. The controller 116 is operatively coupled to the camera 123 for recording images of a vicinity of the robotic cleaning device 100. The first and second line lasers 127, 128 may preferably be vertical line lasers and are arranged lateral of the camera 123. The camera 123 is controlled by the controller 116 to capture and record a plurality of images per second. Data from the images is extracted by the controller 116 and the data is typically saved in the memory 126 along with the computer program 125.

The first and second line laser 127, 128 are configured to scan, preferably in a vertical orientation, the vicinity of the robotic cleaning device 100, normally in the direction of movement of the robotic cleaning device 100. The first and second line lasers 127, 128 are configured to send out laser beams, which illuminate furniture, walls and other objects of e.g. a room to be cleaned. The camera 123 is controlled by the controller 116 to capture and record images from which the controller 116 creates a representation or layout of the surroundings that the robotic cleaning device 100 is operating in, by extracting features from the images and by measuring the distance covered by the robotic cleaning device 100, while the robotic cleaning device 100 is moving across the surface 129 to be cleaned.

It is noted that the side brush 114 may be arranged on a robotic cleaning device 100 which is less complex than that exemplified for illustrative purposes in FIGS. 1 and 2.

Now, in an embodiment, in order to avoid the side brush 114 entangling with fibres of a carpet, or to avoid hampering the capability of the robot 100 to climb over objects such as thresholds, cables and carpet edges, or simply to not permanently have the side brush 114 contacting the surface over which the robotic cleaning device 100 moves, the robotic cleaning device 100 is equipped with a mechanism for retracting the side brush 114 into a space in the main body 111.

FIG. 3 illustrates the robotic cleaning device 100 being equipped with such a mechanism comprising a retractable member 119, such as a rod or a piston, on which the side brush 114 is arranged, and an actuator exemplified by motor 124 for retracting the rod 122 into the space 119 in the main body 111.

Thus, if it no longer is desirable to have the side brush 114 contact the surface 129 to be cleaned, the controller 116 will control the motor 124 to retract the rod 122 into the space 119 such that the side brush 114 advantageously is partly or fully retracted into the space 119 having as a result that the side brush 114 no longer contacts the surface 129. Conversely, should it again be desirable to have the side brush 114 contact the surface 129, the controller 116 will control the motor 124 to extend the rod 122 out from the space 119, whereby the side brush 124 will extend out from the space 119 and finally contact the surface 129 as shown in FIG. 2.

FIG. 4 illustrates the robotic cleaning device 100 being equipped with a mechanism for extracting the rotatable side brush 114 into a space 119 in the main body 111 according to a further embodiment.

In this embodiment, the rotatable side brush 114 is retracted into the space 119 in a direction being axial to the rotational axis of the rotatable side brush 114. Again, the retracting member 122 may be embodied by a rod or piston being retracted into—or extended out of—the space by means of a motor 124 such that the side brush 114 advantageously is partly or fully retracted into/extended out of the space 119 in order to move the side brush 114 in and out of contact with the surface 129.

In the embodiments described with reference to FIGS. 3 and 4, the motor 124 is utilized for causing the retracting member 122 to retract into/extend out of the space 119 in the main body 111, and it may be necessary to equip the robotic cleaning device 100 with a further motor (not shown) for actually rotating the side brush 114.

FIG. 5a illustrates a further embodiment of the mechanism for retracting the rotatable side brush 114 into the space 119 in a direction being axial to the rotational axis of the rotatable side brush 114.

In this embodiment the retracting member is embodied in the form of a threaded rod 122 a located in the space 119, which threaded rod 122 a the motor 124 is arranged to rotate. Further in this embodiment, the space 119 is cylindrically shaped (which may also be the case in the previously illustrated embodiments).

Moreover, the mechanism comprises an annular threaded member 130 to which the side brush 114 is attached, which annular threaded member 130 is arranged to engage with the threaded rod 122 a.

Now, in this embodiment, a diameter of the cylindrically shaped space 119 is adapted to the dimensions of the side brush 114 such that friction is created between the side brush 114 and an interior of the cylindrically shaped space. As can be seen in FIG. 5a , the retracted side brush 114 is in close contact with the interior of the space 119.

Upon the motor 124 starts rotating the threaded rod 122 a in a first direction (i.e. the rotational direction of the rotating side brush 114 when the brush in cleaning mode), the friction between the side brush 114 and the interior of the space 119 will prevent the side brush 114 from rotating—or at least from freely rotating—which has as an effect that the annular member 130 and thus the side brush 114 will move downwards along the threaded rod 122 a and extend out of the space 119 until it reaches an end section 131 of the threaded rod 122 a preventing the annular threaded member 130 to move out of threaded engagement with the threaded rod 122 a.

Conversely, with reference to FIG. 5b , upon the motor 124 starts rotating the threaded rod 122 a in a second direction (i.e. opposite to the rotational direction of the rotating side brush 114 being in cleaning mode), the friction between the side brush 114 and the interior of the space 119 will prevent the side brush 114 from rotating which has as an effect that the annular member 130 and thus the side brush 114 will move upwards along the threaded rod 122 a and retract into the space 119 until it reaches an end position in the form of e.g. a position as measured by a sensor or a timer, or a mechanical end stop or simply an interior end wall of the space 119.

Assuming that the retracted side brush 114 of FIG. 5a is to be extended out of the space 119 and set into cleaning mode, the motor 124 will rotate the threaded rod 122 a in the indicated first direction while the friction between the interior of the space 119 and the side brush 114 will prevent the side brush 114 from rotating.

With reference to FIG. 6a , as a result of the friction, the annular threaded member 130 and thus the side brush 114 will move in downwards direction along the threaded rod 122 a.

Subsequently, as can be seen in FIG. 6b , the annular threaded member 130 and thus the side brush 114 will exit the space 119 and extend out from the main body in and move in a downward direction until the annular threaded member 130 abuts against the end section 131 which prevents the annular threaded member 130 to move out of engagement with the threaded rod 122 a. As can be concluded form FIG. 6b , the rotating side brush 114 is now in cleaning mode.

In this position, if it is desirable that the annular threaded member 130 and thus the rotating side brush 114 is to be retracted into the main body iii of the robotic cleaning device 100, the controller 116 will control the motor 124 to alter the rotational direction of the threaded rod 122 a, in which case friction between the rotating side brush 114 and the surface 129 to be cleaned causes the annular threaded member 130 to move in an upward direction along the threaded rod 122 a to retract into the space 119.

Advantageously, with the embodiment illustrated in FIGS. 5a-b and 6a-b , the motor 124 used for causing the side brush 114 to retract into/extend out of the space 119 is also used for rotating the side brush 114. Hence, a single motor 124 can be used for handling both the retraction/extension as well as the rotation of the side brush 114.

FIG. 7 illustrates a further embodiment, where a spring 132 is arranged between the end member 131 and the annular threaded member 130, the spring being attached to either one of the end member 131 and the annular threaded member 130. Advantageously, by arranging the end member 131 and the annular threaded member 130 to be spring-biased with respect to each other, the friction between the rotating side brush (not shown in FIG. 7) and the surface to be cleaned may be controlled based on degree of stiffness of the selected spring 132.

The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims. 

1. A robotic cleaning device comprising: a main body; a propulsion system configured to move the robotic cleaning device over a surface to be cleaned; a controller configured to control the propulsion system to move the robotic cleaning device over the surface to be cleaned; at least one rotatable side brush arranged to sweep debris from the surface to be cleaned; and a mechanism configured to at least partly retract the at least one rotatable side brush into a space arranged inside the main body upon receiving a control signal from the controller, such that the rotatable side brush is moved out of contact with the surface to be cleaned.
 2. The robotic cleaning device of claim 1, wherein the mechanism comprises: a retractable member coupled to the at least one rotatable side brush and arranged to retract the at least one rotatable side brush into the space; and an actuator arranged to move the retractable member into, or out of, the space upon receiving a control signal from the controller.
 3. The robotic cleaning device of claim 1, wherein the at least one rotatable side brush is configured to be retractable into the space inside the main body in an axial direction with respect to a rotational axis of the side brush.
 4. The robotic cleaning device of claim 3, wherein the space is cylindrically shaped and the mechanism comprises: a threaded rod located in the cylindrically shaped space; an annular threaded member to which the at least one rotatable side brush is attached, the annular threaded member being arranged to engage with the threaded rod; and an actuator configured to rotate the threaded rod; wherein a diameter of the cylindrically shaped space is adapted to a dimension of the at least one rotatable side brush such that friction is created between the side brush and an interior of the cylindrically shaped space, thereby at least partly preventing the at least one rotatable side brush from rotating when in contact with the interior; wherein said friction causes the annular threaded member to move along the threaded rod to extend out from the space in order to have the at least one rotatable side brush rotate and sweep the debris from the surface to be cleaned upon the threaded rod rotating in a first direction, the threaded annular member moving along the threaded rod until it reaches an end member of the threaded rod preventing the annular threaded member to move out of threaded engagement with the threaded rod; and friction between the at least one rotating side brush and the surface to be cleaned causes the annular threaded member to move along the threaded rod to retract into the space upon the threaded rod rotating in a second direction.
 5. The robotic cleaning device of claim 4, wherein the mechanism further comprises: a spring arranged between the annular threaded member and the end member.
 6. The robotic cleaning device of claim 4, further comprising: an opening in a bottom side of the main body via which debris is removed from the surface, wherein the at least one rotatable side brush is arranged adjacent to the opening.
 7. The robotic cleaning device of claim 2, wherein the actuator comprises a motor.
 8. The robotic cleaning device of claim 1, wherein the robotic cleaning device comprises a robotic vacuum cleaner, a robotic sweeper or a robotic floor washer. 